Starting on page 36 we list the 200 richest billionaires who are still building their fortunes — or are working brilliantly with what they’ve inherited. The poorest is worth $1.5 billion. No coupon clippers allowed. Starting on page 73, we list an additional 150 individuals and families worth at least $1 billion. From the 200, we’ve picked 10 who aren’t necessarily the richest but who we think are the smartest entrepreneurs of the group. Seventy of the bunch are Americans; 52 are Europeans; Asians, 44. And we have uncovered 19 global heavy hitters –- tycoons who aren’t billionaires yet, but who do bear watching. Net worths were calculated using stock prices and exchange rates from early May.

On the following pages, you’ll find the world’s richest businessmen.

Americans dominate the list, this year more than ever. Thank sky-high U.S. equity valuations, particularly for many technology stocks. If Federal Reserve Chairman Alan Greenspan is worried the U.S. markets are too high, here’s one more thing to keep him up at night: Bill Gates is worth $51 billion, up from $36 billion 12 months ago. The world’s second-richest man, the Sultan of Brunei, weighs in at a mere $36 billion.

That could be scary for U.S. equity markets.

How so? FORBES has been tracking billionaires for eleven years now, and we’ve seen a pattern emerge: The sudden rise of billionaires in a country or region is often a sign of excessive liquidity and a coming stock market decline that destroys paper fortunes as quickly as they were made.

Step back to our first billionaires list, published in October 1987.

The world’s richest man then was Japanese real estate tycoon Toshiaki Tsutsumi, worth an estimated $20 billion. This was a period in financial history when Japanese banks would finance the most marginal real estate speculator; land prices, and stock prices with them, climbed to exorbitant levels. In 1990 they crashed. Today Tsutsumi is worth just under $6 billion.

In the early 1990s Mexico was generating lots of new billionaires — a record 24 of them on our July 1994 list. Afew months later came the peso crisis.

Today, billionaires are sprouting like weeds in the U.S. The median net worth for a U.S. billionaire is $6.8 billion this year, up from $5.2 billion last year and $2.5 billion in 1996.

To oversimplify somewhat, money now washes around the world, moving in and out of markets as investors’ perceptions about returns in those markets change. Money poured into Mexico in the early 1990s in anticipation of good things from Carlos Salinas‘ economic reforms. The Mexican stock market quadrupled, in dollar terms, from 1990 to 1994, when Mexico’s Carlos Slim Helú was worth $6.6 billion, making him the world’s sixth-richest man.

With the peso crisis capital poured back out. The Mexican market plunged 44%, and by 1995 Slim was down to $3.7 billion.

By then Asia was looking good, so investors and bankers shoveled money into projects there. In 1995 Thailand’s agribusiness tycoon Dhanin Chearavanont was worth $5.5 billion — more than the richest man inEngland or France. Now not a single Thai qualifies for our list.

Money poured out of Asia — where did it go? A lot of it has gone into the U.S., pushing down interest rates and pushing up equity values, and creating huge fortunes.

We don’t know if U.S. equities are in for a tumble, but we (and everybody else) do know that they’re trading at some very fancy valuations. The S&P 500 is at 28 times trailing earnings, its alltime high. Microsoft is selling at 53 times estimated 1998 earnings. Warren Buffett’s Berkshire Hathaway is at 89 times, Michael Dell‘s Dell Computer at 44 times.

If a region’s relative abundance or shortage of billionaires is anything to go by, Europe might be a good place to put some money now.

Of the 350 billionaires we list, 171 are Americans, compared to 73 Europeans — yet Euroland is roughly as rich as the U.S. Punishing tax regimes, rigid labor markets and other obstacles to European wealth creation won’t last forever.

As FORBES GLOBAL has noted (“The equity culture,” June 15), the ratio of the value of publicly traded equity to GDP in the U.S. is 140% — nearly four times greater than the ratio for Germany, France and Italy. And this despite recently strong European stock markets.

Our guess is that these ratios will converge, either because the U.S. market cap falls or the European cap rises (or both). With convergence, Europe could be the next region to grow rich in very rich people.